Pulse width modulated three-phase or multi-phase inverters are used for speed-variable motor applications, as utility interfaces (for example for feeding-in renewable energy) as well as for various other applications.
A three-phase inverter is a device that transforms electrical energy from direct voltage/current to a three-phase alternating current system. Such a device can be unidirectional or bidirectional in terms of the energy transport.
EP 2,107,672 A1 discloses a transformerless three-phase inverter which includes a three-phase bridge circuit and at least one divided intermediate circuit. The neutral conductor of a three-phase AC low-voltage mains is separated from the central point of the intermediate circuit. The inverter is connected to the AC low-voltage mains via a three-conductor mains input.
U.S. Pat. No. 5,341,075 discloses a combined battery recharge and motor drive system which employs an essentially conventional polyphase pulse width modulated (PWM) inverter and a polyphase motor which may be reconnected to operate in a battery recharge mode. Single phase or three-phase AC power from an external source is applied across the reconfigured circuit, and the inverter switches are then controlled to operate as a boost switching regulator. Electrostatic (Faraday) shielding techniques and construction allow extremely small ground currents for improved safety an GFI outlet compatibility.
However, conventional inverters are in many cases complex in construction.